1. Field of the Invention
The present invention relates to a receiver, and more particularly, to a circuit for determining whether a received signal is a high-definition television (HDTV) signal or an analog TV signal, and to a method therefor.
2. Description of Related Art
Tests have been completed of a xe2x80x9cGrand Alliancexe2x80x9d (GA) advanced television (ATV) system, which is a new digital television transmission system standard which can replace the analog national television system committee (NTSC) broadcasting system. A GA-ATV system (also called GA-HDTV or GA-VSB) is standardized by the advanced television system committee (ATSC), and adopts a vestigial side band (VSB) modulation method for digital transmission.
However, when full-scale HDTV broadcasting starts, it cannot avoid coexistence with an existing analog broadcasting system (here, NTSC). Also, a receiver must allow a viewer to watch either HDTV or NTSC broadcasting at will. That is, a channel may be for NTSC TV broadcasting in some areas and for HDTV broadcasting in other areas, so a receiver must have a structure by which either of the two broadcastings can be selected and viewed. Such a simulcast receiver for receiving both HDTV and NTSC TV signals is usually comprised of a tuner, an HDTV signal processor for processing HDTV signals, an NTSC TV signal processor for processing NTSC TV signals, and a display. Accordingly, before an HDTV or NTSC TV signal is selected and displayed on the single display, it must be determined whether the current received signal is an HDTV or NTSC TV signal. A receiver for receiving the HDTV signal also requires a circuit for determining whether the current received signal is an HDTV or NTSC TV signal, in order to display whether a channel selected by a user is an HDTV or NTSC TV channel.
It is an object of the present invention to provide a circuit for correctly determining whether a received signal is an HDTV signal or an analog TV signal upon channel selection in a simulcast receiver.
It is another object of the present invention to provide a circuit for correctly determining whether a received signal is an HDTV signal or an analog TV signal in an HDTV receiver.
It is still another object of the present invention to provide a method for correctly determining whether a received signal is an HDTV signal or an analog TV signal.
It is yet another object of the present invention to provide a method for selecting a received signal in order of priority according to selection of channels, when an HDTV signal and an analog TV signal are simultaneously received.
It is still yet another object of the present invention to provide a method for correctly determining a received signal according to channel selection when an HDTV signal and an analog TV signal are separately processed in a simulcast receiver.
It is further another object of the present invention to provide a method for correctly determining a received signal according to channel selection when an HDTV signal and an analog TV signal are partially processed together in a simulcast receiver.
To accomplish the above objects, a circuit is provided for determining a received signal. This circuit includes both a first detector for detecting a first reference signal included in a received signal and outputting a first detection signal, and a second detector for detecting a second reference signal included in the received signal and outputting a second detection signal. The circuit also includes a generator for generating a determination signal which indicates that the received signal is an analog broadcasting signal, in the event the first detection signal is detected, and which indicates that the received signal is a high definition signal, in the event the second detection signal is detected.
Also, a method is provided for determining whether a received signal is a high-definition signal having a digital format or an analog broadcasting signal. This method includes the step of detecting a first reference signal included in the received signal and outputting a first detection signal, and the step of detecting a second reference signal included in the received signal and outputting a second detection signal. The method also includes the step of generating a determination signal which indicates that the received signal is an analog broadcasting signal if the first detection signal is detected, and which indicates that the received signal is a high definition signal if the second detection signal is detected.